The present embodiments relate generally to an interface for introducing ions into a mass spectrometer, and in particular to an interface that allows both an electrospray nebulizer and its associated mass spectrometer to be at or near electrical ground.
Mass spectrometers are instruments that measure the mass-to-charge ratio of ions. There are many different types of mass spectrometers, including, for example, time-of-flight mass spectrometers, quadrupole mass spectrometers, magnetic sector mass spectrometers, sector quadrupole mass spectrometers, ion trap mass spectrometers, Fourier transform ion cyclotron resonance mass spectrometers, Kingdon trap-based mass spectrometers sold commercially as Orbitrap mass spectrometers, and tandem mass spectrometers. The term “mass spectrometer” is used herein to refer to any of these mass spectrometers, as well as other spectrometers that measure the mass-to-charge ratio of ions.
Mass spectrometers are often coupled with liquid chromatographs, including high performance liquid chromatographs, to analyze materials. For example, a sample of the material may first be separated by a liquid chromatograph into its constituents. The resulting liquid effluent may then be coupled to a mass spectrometer via an electrospray interface. The electrospray interface is used to introduce the sample into the mass spectrometer in the form of charged ions, so that the molecules in the sample can be separated according to their mass-to-charge ratio. In addition to liquid chromatographs, mass spectrometers may also be coupled using an electrospray nebulizer to other sources such as capillary electrophoresis, supercritical fluid chromatography and ion chromatography sources.
Several issued U.S. patents address the problem of interfacing an ion source to a mass spectrometer, including U.S. Pat. No. 4,542,293 to Fenn et al., which discloses an interface from an electrospray ion source to the inlet of a mass spectrometer; U.S. Pat. No. 5,304,798 to Tomany et al., which discloses a housing for converting an electrospray into a desolvated stream for analysis; U.S. Pat. No. 5,736,740 to Franzen, which discloses a device for the transport of ions through a capillary against a potential difference; and U.S. Pat. No. 6,396,057 to Jarrell et al., which discloses an apparatus for coupling the output from a liquid phase separation apparatus to a mass spectrometer. U.S. Pat. No. 4,013,887 discloses a method for separating AC and DC electric fields using homogeneous materials of moderate to high resistivity. Each of these patents is incorporated by reference herein in its entirety.